The Harrier is a ground-based drone, intended for anti-personnel duty. Activating the drone places it on the ground, where it seeks out nearby targets. While the initial duration is short, Skills in the Drones tree can improve it's lifespan. Similarily, uncommon, rare, and epic varients can have an increased duration modifier.
Like turrets, Robotics can only have one drone deployed at a time.
The basic Harrier Drone is available for purchase at level 25 from Dome City's Robotics Gear vendor. A specific epic varient is available for 6000 Mercenary Tokens. Uncommon, rare, and other epic varients are occasionally awared for completing PvE and PvP missions.